1. Field of the Invention
The subject matter of this invention is related generally to operating mechanisms for circuit breaker apparatus and is related particularly to dual, concentric opening and closing coil spring members for circuit breaker operating mechanisms.
2. Description of the Prior Art
It is well known in the prior art to utilize coil springs to provide the force necessary to open and close circuit breaker contacts. Generally in the past, the coil spring for opening the circuit breaker contacts has been physically spaced away from the coil spring for closing the circuit breaker contacts. In addition, one end of each of the springs has been generally affixed to the frame of the circuit breaker mechanism. Examples of such prior art construction are shown in U.S. Pat. No. 3,183,332, issued May 11, 1965 to R. E. Frink et al, U.S. Pat. No. 3,585,330, issued June 15, 1971 to F. Bould, U.S. Pat. No. 3,590,192, issued June 29, 1971 to F. Bould, and U.S. Pat. No. 3,600,540, issued Aug. 17, 1971 to F. Bould. All of the above-mentioned patents are assigned to the assignee of the present application. In addition, U.S. Pat. No. 3,898,409, issued Aug. 5, 1975 to R. Liebig et al shows a similar spaced apart dual spring arrangement. The concept of utilizing separately acting coiled springs, one inside the other, where one is for opening the circuit breaker mechanism and one is for closing the circuit breaker mechanism, where both springs are charged to compression and released from that disposition for providing circuit breaker contact movement has not been found in the prior art. It should be noted that U.S. Pat. No. 3,549,843, issued Dec. 22, 1970 to G. A. Wilson teaches one spring operating inside the other. However, the function of the two coil springs is merely redundant, or supplemental--that is to say, two coil springs are utilized to provide more force than one coil spring could provide for a circuit breaker closing operation. Other prior art which has been found is the German patent open to inspection No. 1,415,646 filed 9th, March 1961 and open to inspection 30th, April, 1969, entitled, "Actuating Device For An Electrical Switch" by W. Zimmermann. In this patent, two coiled springs, one operating inside the other, where one is utilized for opening circuit breaker contacts and one is utilized for closing circuit breaker contacts, is taught. However, in the apparatus taught in the previously described West German patent, it is required that one of the springs operates in tension as the other spring operates in compression. It would be advantageous, therefore, if a dual, concentric, coil spring circuit breaker contact opening and closing apparatus could be found where both of the coiled springs are charged into compression and released from that point for useful operation.